Should mech. vac/boost gauge read 0???

[Timshadi]

A buddy of mine gave me a used mechanical vac/boost Autometer Colbolt series gauge. I didn't install it yet, but noticed its reading 4 psi. Now correct me if im wrong but if the gauge is mechanical and neutral/not hooked up to any vacuum or pressure shouldn't it read "0"?? Does anyone think maybe this gauge is not calibrated right??

 

[AutoEuphoria]

It should read zero when not connected to anything, yes. And those types of gauges are generally pretty cheap, so they are most likely not the most accurate (nothing against AutoMeter itself). It might "fix itself" when hooked up to the car...but I'd give it a test run before actually installing the whole thing. Just get some cheap vacuum line and replace the line that goes to the BPV (so you're not cutting the stock one), then T that off and hook up the gauge. start the car and see if it goes into vacuum. Then shut the car off and see if it centers itself at 0

 

[chubbs]

i think they can be "shaken" and move. i know my greddy electronic will "drop" everytime i shake the car, like close the door. so its hard to say.

 

[MSMS3]

Yes. Tap pretty hard against the side of it. If it does not settle to zero, ditch it and get a good one. VDO makes a great one that is European Sport Sedan OEM quality for about $50 and widely available.

 

[SRTie4k]

You can actually fix the boost gauge by yourself if it doesn't settle on zero. Since it's mechanical, all it uses is a large helical spring inside to push the needle one way or another.

If you remove the backlight and look in through the hole, you should see a brass coil in the back. Take a small screwdriver and move it around inside while watching the dial - the dial should move one way or another. All you do is simply move it around (i.e. lengthen/shorten it by bending it) until the gauge sits on zero. It's a very simple fix.